It is known that in household appliances of the aforesaid type, a number of operative parameters must be known in order to ensure correct operation, such as for example, the weight of the linen contained in the basket, the degree of uniformity with which the linen is distributed in the basket, the pressure and/or quantity of feeding water, etc.
French patent application FR-A-2767194 describes a detection system of a number of such parameters using a pressure switch (pressure transducer) connected to the water feeding system of the household appliance and coupled to a water-tight tank containing the rotating basket of the household appliance (washing machine or dryer); the tank, as known, is connected to the load-bearing frame of the household appliance which supports it by means of elastic, possibly shock-absorbing, elements, making it therefore relatively mobile with respect to the load-bearing frame, consequent to the load applied to it by the basket, which in use contains the linen to be washed or dried.
The pressure switch includes a rigid casing accommodating a deformable membrane sensitive to hydraulic pressure, a ferromagnetic material core fastened to the membrane and a winding carried by the casing and operatively coupled to the core to form a variable inductance electrical inductor. The end-of-stroke stop which defines the system zero position is defined by a spring. In this way, the pressure switch is capable of detecting the hydraulic pressure which acts in use on the membrane, producing a signal (generally linear) correlated to the same and, furthermore, is capable of varying such signal according to the vibrations to which the basket (and consequently the tank with contains it) is subject in use, therefore allowing the generation of an electrical signal indicating the direction and amplitude of the basket vibrations.
The detection system described is not however free from drawbacks; firstly, it does not allow to detect the static load of the basket, i.e. the weight of the linen it contains, which must be set by hand by the user on the control panel of the household appliance, nearly always by approximation and consequently imprecisely. Furthermore, also due to the presence of a “mobile” stop defined by the spring, it is relatively large in size and presents a certain difficulty in assembly, in addition having a relatively high production cost.